网站实现雪花飘落效果
点击查看效果: 雪花飘落
一,在网站页面中引入下方script
即可。
<script src="https://www.vae.zhangweicheng.xyz/web/xuehua/xuehua.js"></script>
二,以下是全部JavaScript代码
// 创建一个立即执行函数
(function() {
// 定义变量
var flakes = [], // 雪花数组
canvas = document.createElement("canvas"), // 创建画布
ctx = canvas.getContext("2d"), // 获取画布上下文
flakeCount = 200, // 雪花数量
mX = -100, // 鼠标X坐标
mY = -100; // 鼠标Y坐标
// 设置画布属性
canvas.setAttribute("id", "snowfall");
canvas.style.position = "fixed";
canvas.style.top = "0";
canvas.style.left = "0";
canvas.style.width = "100%";
canvas.style.height = "100%";
canvas.style.zIndex = "999999";
canvas.style.pointerEvents = "none";
// 将画布添加到body中
document.body.appendChild(canvas);
// 设置画布宽高
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
// 雪花动画函数
function snow() {
// 清空画布
ctx.clearRect(0, 0, canvas.width, canvas.height);
// 循环遍历雪花数组
for (var i = 0; i < flakeCount; i++) {
var flake = flakes[i], // 获取当前雪花
x = mX, // 雪花X坐标
y = mY, // 雪花Y坐标
minDist = 100, // 最小距离
x2 = flake.x, // 当前雪花X坐标
y2 = flake.y; // 当前雪花Y坐标
// 计算距离和方向
var dist = Math.sqrt((x2 - x) * (x2 - x) + (y2 - y) * (y2 - y)),
dx = x2 - x,
dy = y2 - y;
// 如果距离小于最小距离
if (dist < minDist) {
var force = minDist*2 / (dist * dist), // 计算力度
xcomp = (x - x2) / dist,
ycomp = (y - y2) / dist,
deltaV = force / 2;
// 更新雪花速度
flake.velX -= deltaV * xcomp;
flake.velY -= deltaV * ycomp;
} else {
// 如果距离大于等于最小距离
flake.velX *= .28;
if (flake.velY <= flake.speed) {
flake.velY = flake.speed
}
flake.velX += Math.cos(flake.step += .25) * flake.stepSize;
}
// 绘制雪花
ctx.fillStyle = "rgba(255,255,255," + flake.opacity + ")";
flake.y += flake.velY;
flake.x += flake.velX;
// 如果雪花超出画布范围,重置雪花
if (flake.y >= canvas.height || flake.y <= 0) {
reset(flake);
}
if (flake.x >= canvas.width || flake.x <= 0) {
reset(flake);
}
ctx.beginPath();
ctx.arc(flake.x, flake.y, flake.size, 0, Math.PI * 2);
ctx.fill();
}
// 循环调用动画函数
requestAnimationFrame(snow);
};
// 重置雪花函数
function reset(flake) {
flake.x = Math.floor(Math.random() * canvas.width);
flake.y = 0;
flake.size = (Math.random() * 3) + 2;
flake.speed = (Math.random() * 1) + 0.5;
flake.velY = flake.speed;
flake.velX = 0;
flake.opacity = (Math.random() * 0.5) + 0.3;
}
// 初始化函数
function init() {
// 循环创建雪花
for (var i = 0; i < flakeCount; i++) {
var x = Math.floor(Math.random() * canvas.width),
y = Math.floor(Math.random() * canvas.height),
size = (Math.random() * 3) + 2,
speed = (Math.random() * 1) + 0.5,
opacity = (Math.random() * 0.5) + 0.3;
// 将雪花添加到数组中
flakes.push({
speed: speed,
velY: speed,
velX: 0,
x: x,
y: y,
size: size,
stepSize: (Math.random()) / 30,
step: 0,
opacity: opacity
});
}
// 调用雪花动画函数
snow();
};
// 监听鼠标移动事件,更新鼠标坐标
document.addEventListener("mousemove", function(e) {
mX = e.clientX,
mY = e.clientY
});
// 监听窗口大小改变事件,更新画布宽高
window.addEventListener("resize", function() {
canvas.width = window.innerWidth;
canvas.height = window.innerHeight;
});
// 初始化
init();
})();
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